feat: E-Commerce 시스템 확장 및 PG 전략 패턴 적용

build.gradle

@@ -32,8 +32,8 @@ subprojects {
 
     // 공통 의존성
     dependencies {
-        compileOnly 'org.projectlombok:lombok:1.18.32'  // Java 21 호환 버전
-        annotationProcessor 'org.projectlombok:lombok:1.18.32'
+        compileOnly 'org.projectlombok:lombok:1.18.34'  // Java 21 최신 호환 버전
+        annotationProcessor 'org.projectlombok:lombok:1.18.34'
         testImplementation 'org.springframework.boot:spring-boot-starter-test'
 
         // Distributed Tracing - Micrometer + Zipkin

common/src/main/java/com/example/common/config/KafkaConsumerConfig.java

@@ -0,0 +1,59 @@
+package com.example.common.config;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.annotation.EnableKafka;
+import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory;
+import org.springframework.kafka.core.ConsumerFactory;
+import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
+import org.springframework.kafka.support.serializer.JsonDeserializer;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 공통 Kafka Consumer 설정
+ * 모든 마이크로서비스에서 재사용 가능
+ */
+@Configuration
+@EnableKafka
+public class KafkaConsumerConfig {
+
+    @Value("${spring.kafka.bootstrap-servers:localhost:9092}")
+    private String bootstrapServers;
+
+    @Value("${spring.kafka.consumer.group-id:default-group}")
+    private String groupId;
+
+    @Bean
+    public ConsumerFactory<String, Object> consumerFactory() {
+        Map<String, Object> props = new HashMap<>();
+        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
+        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
+        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
+        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class);
+        props.put(JsonDeserializer.TRUSTED_PACKAGES, "*");
+        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, true);
+        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, 1000);
+
+        return new DefaultKafkaConsumerFactory<>(props);
+    }
+
+    @Bean
+    public ConcurrentKafkaListenerContainerFactory<String, Object> kafkaListenerContainerFactory() {
+        ConcurrentKafkaListenerContainerFactory<String, Object> factory =
+                new ConcurrentKafkaListenerContainerFactory<>();
+        factory.setConsumerFactory(consumerFactory());
+
+        // 에러 핸들러 설정 - 재시도 가능한 예외와 불가능한 예외 구분
+        factory.setCommonErrorHandler(new org.springframework.kafka.listener.DefaultErrorHandler(
+                new org.springframework.util.backoff.FixedBackOff(1000L, 3L) // 1초 간격으로 3회 재시도
+        ));
+
+        return factory;
+    }
+}

common/src/main/java/com/example/common/config/KafkaProducerConfig.java

@@ -0,0 +1,47 @@
+package com.example.common.config;
+
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.core.DefaultKafkaProducerFactory;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.kafka.core.ProducerFactory;
+import org.springframework.kafka.support.serializer.JsonSerializer;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 공통 Kafka Producer 설정
+ * 모든 마이크로서비스에서 재사용 가능
+ */
+@Configuration
+public class KafkaProducerConfig {
+
+    @Value("${spring.kafka.bootstrap-servers:localhost:9092}")
+    private String bootstrapServers;
+
+    @Bean
+    public ProducerFactory<String, Object> producerFactory() {
+        Map<String, Object> config = new HashMap<>();
+        config.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
+        config.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
+        config.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JsonSerializer.class);
+
+        // Producer 성능 및 신뢰성 설정
+        config.put(ProducerConfig.ACKS_CONFIG, "1");  // 리더 파티션 ACK (성능과 신뢰성 균형)
+        config.put(ProducerConfig.RETRIES_CONFIG, 3);  // 전송 실패 시 재시도
+        config.put(ProducerConfig.COMPRESSION_TYPE_CONFIG, "snappy");  // 압축
+        config.put(ProducerConfig.LINGER_MS_CONFIG, 10);  // 배치 대기 시간
+        config.put(ProducerConfig.BATCH_SIZE_CONFIG, 16384);  // 배치 크기
+
+        return new DefaultKafkaProducerFactory<>(config);
+    }
+
+    @Bean
+    public KafkaTemplate<String, Object> kafkaTemplate() {
+        return new KafkaTemplate<>(producerFactory());
+    }
+}

common/src/main/java/com/example/common/event/DeliveryCompletedEvent.java

@@ -0,0 +1,38 @@
+package com.example.common.event;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.io.Serializable;
+import java.time.LocalDateTime;
+
+/**
+ * 배송 완료 이벤트
+ * - Delivery Service에서 배송 완료 시 발행
+ * - Order Service가 구독하여 주문 상태를 DELIVERED로 업데이트
+ */
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class DeliveryCompletedEvent implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * 주문 ID
+     */
+    private Long orderId;
+
+    /**
+     * 배송 ID
+     */
+    private String deliveryId;
+
+    /**
+     * 이벤트 발생 시각
+     */
+    private LocalDateTime completedAt;
+}

common/src/main/java/com/example/common/event/DeliveryFailedEvent.java

@@ -0,0 +1,43 @@
+package com.example.common.event;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.io.Serializable;
+import java.time.LocalDateTime;
+
+/**
+ * 배송 실패 이벤트
+ * - Delivery Service에서 배송 실패 시 발행 (수령 거부, 주소 오류 등)
+ * - Order Service가 구독하여 고객센터 처리
+ */
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class DeliveryFailedEvent implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * 주문 ID
+     */
+    private Long orderId;
+
+    /**
+     * 배송 ID
+     */
+    private String deliveryId;
+
+    /**
+     * 실패 사유
+     */
+    private String reason;
+
+    /**
+     * 이벤트 발생 시각
+     */
+    private LocalDateTime failedAt;
+}

common/src/main/java/com/example/common/event/DeliveryStartedEvent.java

@@ -0,0 +1,48 @@
+package com.example.common.event;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.io.Serializable;
+import java.time.LocalDateTime;
+
+/**
+ * 배송 시작 이벤트
+ * - Delivery Service에서 배송 시작 시 발행
+ * - Order Service가 구독하여 주문 상태 업데이트
+ */
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class DeliveryStartedEvent implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * 주문 ID
+     */
+    private Long orderId;
+
+    /**
+     * 배송 ID (추적 번호)
+     */
+    private String deliveryId;
+
+    /**
+     * 배송지 주소
+     */
+    private String address;
+
+    /**
+     * 택배사
+     */
+    private String carrier;
+
+    /**
+     * 이벤트 발생 시각
+     */
+    private LocalDateTime startedAt;
+}

common/src/main/java/com/example/common/event/InventoryReservationFailedEvent.java

@@ -0,0 +1,53 @@
+package com.example.common.event;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.io.Serializable;
+import java.time.LocalDateTime;
+
+/**
+ * 재고 확보 실패 이벤트
+ * - Inventory Service에서 재고 부족 시 발행
+ * - Order Service가 구독하여 주문 취소 처리
+ */
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class InventoryReservationFailedEvent implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * 주문 ID
+     */
+    private Long orderId;
+
+    /**
+     * 상품 ID
+     */
+    private Long productId;
+
+    /**
+     * 요청 수량
+     */
+    private Integer requestedQuantity;
+
+    /**
+     * 현재 재고 수량
+     */
+    private Integer availableQuantity;
+
+    /**
+     * 실패 사유
+     */
+    private String reason;
+
+    /**
+     * 이벤트 발생 시각
+     */
+    private LocalDateTime failedAt;
+}

common/src/main/java/com/example/common/event/InventoryReservedEvent.java

@@ -0,0 +1,54 @@
+package com.example.common.event;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.io.Serializable;
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+
+/**
+ * 재고 확보 성공 이벤트
+ * - Inventory Service에서 재고 차감 성공 시 발행
+ * - Payment Service가 구독하여 결제 처리 시작
+ */
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class InventoryReservedEvent implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * 주문 ID
+     */
+    private Long orderId;
+
+    /**
+     * 상품 ID
+     */
+    private Long productId;
+
+    /**
+     * 상품명 (스냅샷)
+     */
+    private String productName;
+
+    /**
+     * 확보된 수량
+     */
+    private Integer quantity;
+
+    /**
+     * 결제할 금액
+     */
+    private BigDecimal totalPrice;
+
+    /**
+     * 이벤트 발생 시각
+     */
+    private LocalDateTime reservedAt;
+}